@ECHO OFF
SET /A HOUR=%random% %% 24
if %HOUR% lss 10 set HOUR=0%HOUR%
SET /A MINUTE=%random% %% 60
if %MINUTE% lss 10 set MINUTE=0%MINUTE%
SET /A SECOND=%random% %% 60
if %SECOND% lss 10 set SECOND=0%SECOND%
ECHO %HOUR%:%MINUTE%:%SECOND%
SET HOUR=
SET MINUTE=
SET SECOND=
ECHO ON